To paint with oil pastels or watercolor on top of life drawings, you have to make your paper waterproof. You can use clear gesso or gel medium to do so.
Clear gesso or gel medium for making your life drawings paper waterproof?
How to paint flowers from imagination with acrylic ink on canvas
Yupo paper demonstrations Archives - ARTiful: painting demos
Mixed media Archives - ARTiful: painting demos
How to Prime a Canvas using Gesso for Acrylic Painting
Night Time on Irvington, by Kristine Monaco Pastel artwork, Painting, Painting & drawing
340 idées de Y Pastel peinture, peinture pastel, paysage pastel
Archival Ink - Bible Art Journaling Challenge Week 14 - Rebekah R Jones
Tips Archives - ARTiful: painting demos
The Art Cottage: Oil Pastel Demonstration Oil pastel art, Oil pastel, Oil pastels painting